Function of Interferon Inducible Transmembrane Proteins (IFITMs) in the White Pekin Duck

• Author / Creator

  Blyth, Graham AD

• Interferon Inducible Transmembrane Proteins (IFITMs) can restrict the entry of a wide range of viruses. IFITM3 localizes to endosomes and can potently restrict the replication the influenza A virus (IAV), and several other viruses that also enter host cells through the endocytic pathway. Given the major contribution of mammalian IFITM3 to restriction of IAV I investigated whether IFITMs were involved in protection in ducks, the natural host of influenza. Ducks and wild waterfowl are the environmental reservoir of all avian influenza viruses, and often display little to no disease symptoms after infection. I identified and sequenced duck IFITM1, IFITM2, IFITM3 and IFITM5. Using qPCR I demonstrated upregulation of these genes in lung tissue in response to highly pathogenic IAV infection 400-fold, 30-fold, 30-fold and 5-fold, respectively. I cloned and expressed each IFITM in chicken DF-1 cells and showed duck IFITM1 was expressed at the cell surface, while IFITM3 localizes to LAMP1 containing compartments. DF-1 cells stably expressing duck IFITM3 restrict replication of H1N1, H6N2 and H11N9 IAV strains, but not vesicular stomatitis virus. I generated chimeric and mutant IFITM3 proteins and show duck IFITM3 does not require its N-terminal domain for endosomal localization or antiviral function, however, this N-terminal end confers endosomal localization and antiviral function on IFITM1. In contrast to mammalian IFITM3, the conserved YXXθ endocytosis signal sequence in the N-terminal domain of duck IFITM3 is not the sole contributor to correct endosomal localization. Despite significant structural and amino acid divergence duck IFITM3 is functional against AIV.

• Subjects / Keywords

  • Comparative immunology
  • Interferon stimulated genes
  • Avian influenza

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3901ZT7R

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.